In the field of orthopedics, prosthetic devices, such as artificial joints, are often implanted or seated in a patient's body by seating the prosthetic device in a cavity of a bone of the patient. Typically, the cavity must be created before the prosthesis is seated or implanted, and traditionally, a physician removes and or compacts bone to form this cavity. A prosthesis usually includes a stem or other protrusion that serves as the particular portion of the prosthesis that is inserted into the cavity.
To create such a cavity, a physician may use a broach, which broach conforms to the shape of the stem of the prosthesis. Solutions known in the art include providing a handle with the broach, which handle the physician may grasp while hammering the broach into the implant area. Unfortunately, this approach is clumsy and unpredictable as being subject to the skill of the particular physician. This approach almost will always inevitably result in inaccuracies in the location and configuration of the cavity. Additionally, the surgeon suffers from fatigue in this approach due to the constant hammering. Finally, this approach carries with it the risk that the physician will damage bone structure in unintended areas.
Another technique for creating the prosthetic cavity is to drive the broach pneumatically, that is, by compressed air. This approach is disadvantageous in that it prevents portability of an impacting tool, for instance, because of the presence of a tethering air line, air being exhausted from a tool into the sterile operating field and fatigue of the physician operating the tool. Further, this approach, as exemplified in U.S. Pat. No. 5,057,112, does not allow for precise control of the impact force or frequency and instead functions very much like a jackhammer when actuated. Again, this lack of any measure of precise control makes accurate broaching of the cavity more difficult.
A third technique relies on computer-controlled robotic arms for creating the cavity. While this approach overcomes the fatiguing and accuracy issues, it suffers from having a very high capital cost and additionally removes the tactile feedback that a surgeon can get from a manual approach.
A fourth technique relies on the author's own prior disclosures to use a linear compressor to compress air on a single stroke basis and then, after a sufficient pressure is created, to release the air through a valve and onto a striker. This then forces the striker to travel down a guide tube and impact an anvil, which holds the broach and or other surgical tool. This invention works quite well, but, in the process of testing it, does not allow for a simple method to reverse the broach should it become stuck in the soft tissue. Further, the pressure of the air results in large forces in the gear train and linear motion converter components, which large forces lead to premature wear on components.
Consequently, there exists a need for an impacting tool that overcomes the various disadvantages of the prior art.